Extracted stay points:
laltitude	longitude	arriving time	leaving time
40.00754164583334 116.31993147916666 2009-06-12,22:11:16 2009-06-13,01:15:58
40.093137285714285 116.08238283361337 2009-06-13,03:51:23 2009-06-13,05:15:37
40.09315100485435 116.0817368009709 2009-06-13,05:15:42 2009-06-13,06:03:08
40.10130280465119 116.08367837674415 2009-06-13,07:39:29 2009-06-13,08:15:24
